The present invention relates to an integrated liquid crystal display apparatus having a function of an image sensor, and particularly it relates to the constitution of an image sensor part.
A liquid crystal panel, in which a liquid crystal is oriented by applying a voltage to a liquid crystal layer from pixel electrodes, to form an image on a display part, has been known.
A constitution of a conventional liquid crystal panel is briefly described below.
An element substrate comprises an insulating substrate having thereon a display part comprising thin film transistors and a peripheral circuit. The element substrate and a counter substrate are adhered by a sealing material with ensuring a gap between the substrates by a spacer. A liquid crystal is contained between the element substrate and the counter substrate.
The liquid crystal is sandwiched by the pair of substrates and surrounded by the sealing part.
As shown in FIG. 2, the sealing part of the panel is arranged to surround the display part or the display part and the peripheral driver circuit.
In the conventional constitution, the element substrate means a substrate in which an active matrix circuit and the peripheral circuit are provided. The counter substrate arranged as facing the element substrate, in which a counter electrode and a color filter are provided.
In the conventional constitution, a resin for sealing having an ultraviolet setting property or a thermosetting property is used as the sealing material.
An image sensor, on the other hand, has been widely used as an optical sensor converting an image to an electric signal in a copying machine, a digital still camera, a video camera and a facsimile machine.
Recently, a miniature system for incorporating an image and displaying the image is demanded. As a constitution meeting such a demand, a liquid crystal display device with which a sensor module such as a CCD is integrated is considered, but there are problems in consumption power (about 5 W), production cost and size.
The inventors of the invention intend to produce a liquid crystal panel and an image sensor on one substrate by using a MOS thin film transistor.
By using such a constitution, the apparatus can be miniaturized and of a low consumption power (about 50 mW) and low cost.
In the case where a liquid crystal panel and an image sensor are produced on one substrate, the arrangement of the panel and the image sensor and the constitution of the seal become important issue.
An object of the invention is to provide a liquid crystal display panel having a display part and an image sensor on one substrate, which has high reliability and an image sensor of low cost.
The structure of the liquid crystal panel shown in FIG. 1B corresponds to those shown in FIGS. 4A and 4B.
The invention relates to, as a first aspect, a liquid crystal display apparatus comprising a liquid crystal display part comprising an active matrix circuit, a peripheral driver circuit for driving the active matrix circuit, and a sensor part, integrated on one substrate, wherein the sensor part 120 has a sealed space 307 sealed by a sealing part 104 and a counter substrate 302. By employing such a constitution, the sealed space is completely shielded from an external atmosphere by the substrates and the sealing part, as shown in FIGS. 8A and 8B.
Furthermore, the counter substrate may be adhered in an inert gas atmosphere to fill the sealed space with an inert gas (such as Ar and N2), so as to prevent deterioration of the sensor part due to a reaction with oxygen contained in the air.
By sealing the sensor part with the sealing part and the counter substrate, an effect is obtained in that inclusion of the liquid crystal and dusts into the sensor part and a damage such as a flaw of the sensor part occurring on an injection step of the liquid crystal can be prevented.
The invention relates to, as a second aspect shown in FIG. 1A, a liquid crystal display apparatus comprising a liquid crystal display part comprising an active matrix circuit, a peripheral driver circuit 111 for driving the active matrix circuit, and a sensor part 120, integrated on one substrate,
wherein the sensor part 120 is surrounded by at least one sealing part 104, and
a sealing part 103 provided between the liquid crystal display part and the sensor part seals the liquid crystal and protects the sensor part.
By employing such a constitution, inclusion of the liquid crystal and dusts, generation of static charge, and an external impact can be prevented in the sensor part after the adhering step.
Alternatively, as shown in FIGS. 1B, 4A and 4B, the sensor part may be doubly surrounded by plural sealing parts. The outer sealing part functions as a dummy seal. By employing such a constitution, the sensor part 120 can be further prevented from dusts, static charge and external pressures, and the distance between the substrates can be sufficiently maintained. The sensor part may further be surrounded by plural sealing parts in three times, four times or more, or plural sealing parts may be arranged as a dummy seal outside the sealing part of the sensor part.
The invention relates to, as a third aspect, a liquid crystal display apparatus comprising a liquid crystal display part comprising an active matrix circuit, a peripheral driver circuit for driving the active matrix circuit, and a sensor part, integrated on one substrate, wherein a spacer 306 is not present in the sensor part. When the number of the spacers in the sensor part is larger than that in the liquid crystal part, they becomes obstacles upon incorporating an image. Thus, as shown in FIG. 4B, it is preferred that no spacer is present between a receptor of the sensor part and the counter substrate. By employing such a constitution, an image can be incorporated with good quality while uniformly maintaining the distance between the substrates.
Since the sensor part is an element that reacts against external heat, it is preferred that the sensor part is arranged with a sufficient distance to a heat generating circuit such as the peripheral driver circuit, i.e., at a position that is less affected by heat.
By employing such a constitution, the sensor part can be protected from external electrical influence, thermal influence and other physical influence.
In the image sensor of the invention, as shown in FIG. 3A, photo carriers are generated by an amorphous silicon layer 352 having a large light absorption coefficient to visible lights, and the readout of the signals is controlled with a polycrystalline silicon TFT having a large mobility as a switching element.
In the invention, an image sensor formed by the thin film technique and the thin film transistors constituting the display part are formed on one substrate, and an apparatus is obtained at low cost.
The display apparatus of direct vision type containing an image sensor is becoming large scale in future. The substrate is also becoming large scale due to a multi-panels substrate for reducing the production cost.
On the other hand, the sensor part, which is demanded to have a large number of pixels and a miniaturized optical system, is being miniaturized to have a reduced pixel area, and therefore the difference in pixel area between the sensor part and the display part becomes large.
The invention relates to, as a fourth aspect, a liquid crystal display apparatus comprising a liquid crystal display part comprising an active matrix circuit, a peripheral driver circuit for driving the active matrix circuit, and a sensor part, integrated on one substrate, wherein a color filter formed on a counter substrate of the sensor part has a cell size that is smaller than that formed on a counter substrate of the display part.
By employing such a constitution, a liquid crystal display panel can be obtained at low cost, in which the sensor part that has a small pixel area and can incorporate an image with good quality is formed on the same substrate as the liquid crystal display part.
The invention relates to, as a fifth aspect shown in FIG. 6B, a liquid crystal display apparatus comprising a liquid crystal display part comprising an active matrix circuit, a peripheral driver circuit for driving the active matrix circuit, and a sensor part, integrated on one substrate, wherein the thickness d1 of a counter substrate of the sensor part is smaller than the thickness d2 of a counter substrate of the liquid crystal display part.
By employing such a constitution, the influence on the optical system attached to the sensor part can be reduced. The thinner the thickness of the counter substrate of the sensor part is, the less the light is refracted, and thus the intensity of light can be maintained to obtain a liquid crystal display panel at low cost, in which the sensor part that has a small pixel area and can incorporate an image with good quality is formed on the same substrate as the liquid crystal display part. The thin counter substrate of the sensor part in the invention includes colorless transparent substrates or films and is not limited to a glass substrate or a quartz substrate.
The invention relates to, as a sixth aspect shown in FIG. 6C, a liquid crystal display apparatus comprising a liquid crystal display part comprising an active matrix circuit, a peripheral driver circuit for driving the active matrix circuit, and a sensor part, integrated on one substrate, wherein the line width of the sealing part surrounding the sensor part is smaller than the line width of the sealing part surrounding the liquid crystal display part.
By employing such a constitution, when a thin substrate is used in the sensor part, the sealing part can be prevented from inclusion in the sensor part, and the substrate can be prevented from cracking.
The invention relates to, as a seventh aspect shown in FIG. 6D, a liquid crystal display apparatus comprising a liquid crystal display part comprising an active matrix circuit, a peripheral driver circuit for driving the active matrix circuit, and a sensor part, integrated on one substrate, wherein a counter substrate of the liquid crystal display part is maintained at a constant substrate distance by the sealing part and a spacer, and a counter substrate of the sensor part is in close contact with the substrate by an adhesive 515.
By employing such a constitution, the sensor part can be completely isolated from the external atmosphere, and deterioration due to contact with the external atmosphere can be prevented. Because the space 507 between the counter substrate and the element substrate of the sensor part brings about refraction of light, the counter substrate and the element substrate is preferably in as close contact therewith as possible, as similar to the thickness of the counter-substrate.
In order to have the fourth to seventh constitutions, precision is required in mating the sensor part having a small cell size and the counter substrate on the step of adhesion to the counter substrate. Therefore, the counter substrate of the sensor part and the counter substrate of the liquid crystal display part are adhered separately from each other.
The invention relates to a process for producing a liquid crystal display apparatus containing an image sensor and comprising a liquid crystal display part comprising an active matrix circuit, a peripheral driver circuit for driving the active matrix circuit, and a sensor part, integrated on one substrate, the process comprising in this order
a step of adhering a counter substrate of the liquid crystal display part,
a step of cutting the counter substrate of the liquid crystal display part, and
a step of adhering a counter substrate of the sensor part.
As shown in FIGS. 6A to 6D, the display part and the sensor part are formed on one substrate, but the counter substrates 502 and 503 are separated from each other in the display part and the sensor part.